Why is a pencil sharpener

I thought that the “why” phase would be fun, but I have to admit, I’m getting easily stumped.

– Momma, what is that?
– It’s a pencil-sharpener.
– Why?
– Because sometimes pencils need to get sharper.
– Why?
– Because pencils wear down, they start to write messy, and then we use a pencil-sharpener to make them write better.
– Why?
– Because it’s good to have sharp pencils.
– Why?
– Hey, Sophie, do you want to build a tower now?
– Momma, why is a pencil sharpener? Why?